Subterranean heaters have been used to heat subterranean geological formations in oil production, remediation of contaminated soils, accelerating digestion of landfills, thawing of permafrost, gasification of coal, as well as other uses. Some examples of subterranean heater arrangements include placing and operating electrical resistance heaters, microwave electrodes, gas-fired heaters or catalytic heaters in a bore hole of the formation to be heated. Other examples of subterranean heater arrangements include circulating hot gases or liquids through the formation to be heated, whereby the hot gases or liquids have been heated by a burner located on the surface of the earth. While these examples may be effective for heating the subterranean geological formation, they may be energy intensive to operate.
U.S. Pat. Nos. 6,684,948 and 7,182,132 propose subterranean heaters which use fuel cells as a more energy efficient source of heat. The fuel cells are disposed in a heater housing which is positioned within the bore hole of the formation to be heated. The fuel cells convert chemical energy from a fuel into heat and electricity through a chemical reaction with an oxidizing agent. U.S. Pat. No. 7,182,132 teaches that a common central electrical conductor of sufficient size is used to conduct the electricity produced by all of the fuel cells. Similarly, a common return cable is used to complete the electric circuit. As a result, there is no ability to monitor or control individual sections of the subterranean heater. It may be desirable to control the thermal output of individual sections of the subterranean heater in order to tailor the thermal output of individual sections of the subterranean heater to coincide with the geology that may vary over the length of the bore hole.
What is needed is a heater which minimizes or eliminates one of more of the shortcomings as set forth above.